The present invention relates to a gas turbine combustor, a combustion method of the gas turbine combustor and a method of remodeling a gas turbine combustor.
Examples of conventional gas turbine combustors using both a premixed combustion method and a diffusion combustion method are disclosed by Patent Documents 1 and 2, etc.
[Patent Document 1]
Japanese Patent Laid-open No. 11-94255
[Patent Document 2]
Japanese Patent Laid-open No. 3-255815
With the technique described in Patent Document 1, liquid fuel not evaporated completely and remained in the evaporating process after injection sticks to the flame stabilizers as it is. The stuck fuel is carbonated, and this is likely to cause a caulking phenomenon. This poses problems that self-ignition of air fuel mixture due to the char and flashback caused by flame flowing into the premixed combustion burner occur. There arise other problems that cooling performance is lowered at the char stuck portion of a structure and peeling-off chars collide against another structure to damage it. Further, the system has to be complicated because pre-evaporation premixed system is used together with the diffusion combustion system, which requires a means of preventing caulking in the fuel nozzle and maintenance work.
With the technique described in Patent Document 2, the same problems as described above occur even when the pre-evaporation premixed combustion system uses liquid fuel. Further, when a plurality of combustors are disposed on the outer circumference of a gas turbine, and premixed combustion burners are coaxially disposed on the outer circumference of a diffusion combustion burner which is a pilot burner, air for premixing covers around diffuse flame which is a pilot flame. This poses a problem that the diffusion flame cannot reach the cross-fire tube connected to the side wall of the combustor, which makes it impossible to ignite the adjacent combustor.
Further, when pre-evaporation mixing is made using liquid fuel, pre-evaporation cannot be made because air temperature at the time of ignition is too low. This requires use of a pilot burner, and the above-described problem with flame transmission becomes more significant.